It has been proposed in Kunder U.S. Pat. No. 3,395,112, July 30, 1968 discloses certain nickel organophosphites as stabilizers for olefin polymers. In addition, ultra-violet light absorbers and thiodipropionates or organotriphosphites can be employed. Such materials are not nickel complexes with trivalent phosphorus compounds. Kunder, on col. 3, lines 11-20, shows that nickel forms two types of compounds in one of which the nickel is attached to organic radicals by coordinate bonds in which nickel has an apparent valence of four and in the other of which the bonds are ionic and the nickel is bivalent. Kunder mentions that only the latter type compounds have been found to be stabilizers for polyolefins. No mention is made of coordination complexes where nickel has a valence of 0 or a positive valence, e.g. of two.
Salts of nickel (and other metals) with organic phosphites having a free hydroxyl group of course, are well known as antioxidants for polyolefins, e.g. note Kiyawa U.S. Pat. Nos. 3,412,118 Nov. 19, 1968, Marinaccio 3,481,897 Dec. 2, 1969. These compounds are not coordination complexes.
The use of a special type of trivalent organo phosphorus copper complex as flame retardants for polymers including polyethylene is proposed in Grayson U.S. Pat. Nos. 3,294,870, Dec. 27, 1966 and Grayson Pat. 3,345,392, Oct. 3, 1967. The Grayson complexes are complexes of cuprous salts with ethylene bis(aryl or cyanoethyl phosphines). There is no indication of improved ultraviolet light stability.